Astronomers get
excited when a comet comes close to Earth, not only because it
becomes visible, but because with a spacecraft, they can observe it
"up close." Scientists even hope a robot satellite will
soon be able to collect a sample of a comet and bring it back
to Earth.

In the last 4.5 billion years, Earth has been very hot, cooled, had ice ages, and has developed soils, seas, weather, and life. How did all this happen? We know energy from the Sun was part of the process.

Comets in the
Oort
Cloud started with the same materials that planets like Earth were made from. But comets have spent most of their time far away from the Sun, and have not changed and evolved the way the planets have.

Comet

Earth

So studying a piece of a comet would be like
examining a piece of the earth from millions, or even billions of years
ago! Comets may eventually help us find out how DNA, the blueprint of
life, was created from the simple compounds of the original solar nebula,
and finally, how complex plants, people, and animals came to be!

The Latest

In the year 2000, a new comet was discovered, headed for the Sun. It was named Comet Linear. As it got closer to the Sun, the comet got so hot that it broke apart. Some
astronomers think the bright specks you see in this picture of the
broken comet may be the original
planetesimal building blocks of the comet. These exposed parts of the
comet nucleus offer an exciting chance for researchers to study the core of
the comet just as it was created in the early solar system about 4.5 billion
(4,500,000,000) years ago.

Would you like to find out what Comets are made of? Would you like to make one
yourself?

This is the end of the Comet Origins
section. Click Continue to play the game, "What's In a Comet
Anyway?"